One of the apparatuses known in the conventional art is a drive apparatus that positions a movable member by sliding movement, of a drive friction member, by an electromechanical transducer such as a piezoelectric element. The drive apparatus is available in two types—an impact type drive apparatus wherein the piezoelectric element does not move as described in the Patent Document 1, and a self-propelled type drive apparatus wherein the piezoelectric element is held by a movable member and moves together with the movable member as described in the Patent Document 2.
As disclosed in the Patent Document 2, the conventional self-propelled type drive apparatus uses a fixed guide member along which the drive friction member slides, and a biased guide member that is biased to press the drive friction member against the fixed guide member.
However, in the conventional drive apparatus, the frictional force between the drive friction member and fixed guide member is kept constant only when there is a complete agreement between the movable direction of a driven member such as a stage which is driven by the movable member and the direction wherein the fixed guide member is installed.
The fixed guide member and biased guide member are required to be made of a highly rigid material of stable frictional force. This requirement has been a cause for increased costs.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-80964
Patent Document 2: Japanese Unexamined Patent Application Publication No. H10-225150